Scientific Lectures. 177 



siveness, and accurate workmansliip. The Britannia and Niagara 

 bridges are but types of thousands of similar structures all over the 

 world. The Great Eastern steamship of 22,500 tons is premature bj 

 only a few years, for those of 6,000, 7,000, and even 9,000 tons are 

 now built. And the enormous engines and ponderous masses of metal 

 required by them, have taxed the inventive power of the mechani- 

 cians. 



, Canals. 



The great canals executed in our day form an important feature in 

 this progress. I shall endeavor to illustrate my subject, as far as pos- 

 sible, by American examples, and will, therefore, next refer to the 

 Erie canal, and the more so, because in conversation with many, 

 otherwise well informed persons, I find that they do not fully appre- 

 ciate the importance of this great work upon nearly all of the 

 interests of this city, of this State, and of the nation itself. "With 

 many persons there is an idea that the railway has superseded the 

 canal, find that the former now performs the chief part of the trafiic 

 of the country. While the latter is true in regard to interior short 

 lines of trade, it is a serious error, in reference to the great transport 

 between the agricultural west and the Atlantic. The Erie canal, dur- 

 ing the season of navigation, conveys more of this traffic than all of 

 the railways together ; more than all of the trunk lines from the St. 

 Lawrence to the Potomac. The boats which come to tide water have 

 an average cargo, exceeding that carried by the longest freight train 

 on the Central railway. During the busy sotison more than 150 such 

 boats arrive daily, and their tonnage would require more than 150 

 freight trains. The greatest number is but thirty per day on the 

 Central railway. The Erie canal, therefore, is performing more than 

 five times as much business as the Central railway. Yet the slow 

 plodding canal boat attracts no attention, though burdened with more 

 tons than the bustling, noisy, whirling freight train, which creates a 

 sensation in every village through which it passes. The 4,000 canal 

 boats, of an aggregate of 1,000,000 of tonnage, moving 5,000,000 of 

 cargo per annum, exceeds the tonnage of all the vessels engaged in 

 the foreign commerce of this city (even before the war). In another 

 place I have alluded to the great trade of the west, which will soon 

 exceed the capacity of even this enlarged canal, and require it to be 

 again enlarged for vessels of 1,000 tuns, or three times those now in 

 use. A few days since the State Engineer informed me that there 



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